I'm Stickimg with you

[smithers]

How does glue work

[KARL]

This question does not have a single answer but here is my attempt at clarifying at least two different ways. The most common (and probably the oldest) form of bonding relies on the porosity of the material of the two bodies being glued together. In this case the glue seeps into the surface of both parts before setting and thus attaching the two "halves" to each other in a mechanical fashion - the strength of the bond is essentially dependent on the strength of the material the glue is made of. an example would be when two pieces of a teacup are glued together with something squeezed out of a tube. In the other type of bonding the glue is often quite liquid and the two non-porous surfaces are pressed against each other with aim that the adhesive should totally fill the void (gap) between the two, however tiny it is. Once the adhesive has set it will not allow air to enter between the two attached pieces so they can come apart, and it is thus largely atmospheric pressure which holds them together - this phenomenon is commonly demonstrated in physics classes in school (or at least used to be). An example of this type of bonding would be when two pieces of glass are stuck together with something like superglue.

[KARL]

P.S. An example of the force of bonding relying on atmospheric pressure is when the lid of a new jar is extremely difficult to remove. There is usually absolutely no material (jam, sauce, etc.) holding the lid to the glass because the area is factory clean, only the friction between lid and jar contributes to the "bond". In fact the lid is sucked on or, more correctly, pushed on by atmospheric pressure in all likelihood due to the fact that the contents were poured in while hot, the lid screwed on, and then as the contents and air inside cooled off they shrank and created a reduced pressure (vacuum) inside the jar. This very simple but perfect seal keeps airborn contamination from getting in. By far the most reliable and simplest way to break this particular seal is to put the jar in hot water for a few minutes to allow the contents (including air) to expand again (raising the internal pressure again) and you should find the lid comes of quite easily.